In the side airbag device for a vehicle that is set forth in following Patent Document 1, an airbag has a rear side tube bag portion that, at a time of inflation and expansion, extends in the vertical direction at the side further toward the vehicle rear than a vehicle transverse direction outer side end of the chest portion of a seated passenger, and a front side tube bag portion that is positioned further toward the vehicle front side than the rear side tube bag portion and further toward the vehicle front side than the vehicle transverse direction outer side end of the chest portion of the seated passenger and that extends in the vertical direction. The upper portion of the rear side tube bag portion is made to be a shoulder restraining portion that is positioned at the side of the shoulder portion of the seated passenger and restrains the shoulder portion. The upper edge of the front side tube bag is made to be an arm support portion that is at a position lower than the armpit of the seated passenger further toward the vehicle front side than the shoulder restraining portion, and on which the upper arm portion of the seated passenger is placed.
Namely, at this side airbag device for a vehicle, the shoulder portion of the seated passenger, that has relatively high resistance, is restrained by the shoulder restraining portion, and on the other hand, the upper arm portion becoming interposed between the airbag and the chest portion of the seated passenger, that has relatively low resistance, is suppressed due to the upper arm portion of the seated passenger being placed on the arm support portion.